Linda Thoren

What I understand from your screen-shot, is that you have 2 orientations, one string in each orientation, both with 6 modules in series. The total Nominal PV power is 5kWp. In your configuration you have 2 inverters of 5kW, one for each orientation and thus it is strongly oversized. By mixing the two orientation (In the “Sub-array name and Orientation” box) and keep your entire PV Array as one sub-array with 6 modules in series in 2 strings, PVsyst allows you to use only one inverter for the two strings, see screen-shot below. You are though obliged to have one string per orientation.

According to your attached picture, the average length of one string (including 23 modules) is 33m and no distance from the main box to the inverter. We've identified a bug that will be addressed in the next version. It is marked here that you have 8 inverters, even though you've indicated in your message that you only have one (I assume with 8 MPPT inputs, causing PVsyst to incorrectly register 8 inverters). If you want to be sure to take all the losses into account, it is always possible to slightly increase the Loss fraction at STC from the calculated values, as suggested earlier.

Dear Michalis Angeli, Power optimizers are electronic devices, which aim to draw the maximum energy possible from the PV modules within an array (i.e. they try to ensure that each module is working at its MPP at any time). The benefit we can expect from Optimizers is the recovery of electrical mismatch losses. Your choice comes down to what kind of configuration your system have and what level of detail you will construct in the 3D scene. By choosing According to module strings, you will in the construction of the 3D scene, define a partition in module strings. This option will calculate a shading factor "According to strings", representing a higher limit for electrical effects. The partition model for electrical shadings is an approximation that allows to compute electrical shading losses faster than with the detailed "Module Layout" mode. This approach works best in regular row-based systems. By choosing Detailed electrical calculation (acc. To module layout) you have to start by specifying a detailed "Module layout" configuration, you can ask to compute the shadings according to detailed electrical losses. The Module Layout tool is aimed at the detailed calculation of the Electrical shadings mismatch loss. It requires a description of the position of each PV module in the 3D scene, and the module interconnection as strings according to the inverters defined in the "System" part. Regards

Dear Mohamed, You can find a template for the PVsyst format for the Horizon file in the folder “templates” in your workspace. The format Horizon file should contain one line per defined point. Each point defined as an Azimuth and a Height value, expressed in degrees. You would either have to completely restructure your TMY hourly data, going from -180 to 180 degrees with corresponding height values, or import the horizon from web sources. If you wish to use the meteorological data from your site, you can do so by importing your file as a Custom file. You do this by opening Databases, Custom file, choose your Source file and go through the necessary step to do the conversion to import your site. Once saved in your workspace you can use this your created site in your projects. Regards

Dear Angel Mlga, Indeed it seems to be a problem here that I do not have a direct answer to. To address this, I recommend exporting your project as a zip file and sending it to support@pvsyst.com. This way, we can examine your system and provide the assistance you need. Regards

Dear Dominik Damberger In most cases, the open-circuit voltage (Voc) of a PV module will increase as the temperature decreases. This phenomenon is known as the temperature coefficient of voltage, and it's a fundamental characteristic of solar panels. However, at very cold temperatures, such as those below -20°C, will have adverse effects on the performance of a PV module because of mechanical stress on the components etc. The Temperature coefficient is defined by the manufacturer. So, while the temperature coefficient generally causes an increase in Voc, at temperatures below -20°C, other factors related to extreme cold can impact the overall performance and efficiency of a PV module.

Dear Michalis Angeli, In the Wiring layout you should define the average length for one string (blue) and the distance to the main box to the inverter (green). If you have multiple strings and/or inverters this will be reflected in the Global array and the Field global wiring resistance. See example below. It is this number that will be used in the simulation. If you wish to simulate a more pessimistic scenario, to be on the safe side, you can artificially increase the Loss fraction at STC to, for instance 0.8%, compared to the calculated values of 0.65 from the example.

Hello, Adding transformers results in a reduced current load for each individual transformer. The Loss fraction at STC thus decrease at each transformer, but to evaluate the entire system you have to run a simulation and look at the loss diagram.

Dear Michalis Angeli, There are no default values for the output parameters of an inverter, as these values are contingent on the specifications of your inverter model. Consult the inverter’s data sheet to see its specification.